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Post by Carlos (frmaiz) on Sept 1, 2014 11:34:24 GMT -6
How many days are considered average in the Hereford breed and what is the normal variance?
Heifers bred at 14-15 months have the same gestation length a mature cows?
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Post by hoekland on Sept 1, 2014 11:36:18 GMT -6
285 + - 14 days. Heifers usually carry a day or so shorter than mature cows in my experience.
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Post by larso on Sept 1, 2014 14:08:29 GMT -6
How much influence does the bull have on gestation length, I have heifers about to calve and the ones in calf by a certain bull look more forward than some of the others ?
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Post by larso on Sept 1, 2014 15:38:52 GMT -6
I have also been told (whether fact or fiction) that it is the calf's responsibly to present itself for birth, and lazy bulls will generally give you more breach births. Has anybody got any thoughts on whether this could possibly be true all not.
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Post by shumakerherefords on Sept 1, 2014 16:15:08 GMT -6
Wonder if anyone has studied the effect of weather on gestation length? Last year I had 2 calves born earlier than normal and these calves were from 2 different sires. One sire was hauled to the pasture on the 28th of May 2012 and the other was turned into the pasture on the 29th of May 2012. The 2 calves were both bulls and born on 16 and 17 February 2013. The rest of the calves started coming on March 7 2013.
The reason I ask is that we had an unusually hot summer in 2012.
In response to Larso: Years ago I had a discussion with the people at Kstate who were involved with the cloning project. They told me that normally the calf somehow signals the mother that it is ready to be born. With the clones that did not work and they had to induce labor. However it seems to work normally with embryo transplant.
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Post by hoekland on Sept 1, 2014 23:57:26 GMT -6
I have also been told (whether fact or fiction) that it is the calf's responsibly to present itself for birth, and lazy bulls will generally give you more breach births. Has anybody got any thoughts on whether this could possibly be true all not. The longer legged the calves are the more malpresentations, not so sure about laziness. |
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Post by hoekland on Sept 1, 2014 23:58:31 GMT -6
How much influence does the bull have on gestation length, I have heifers about to calve and the ones in calf by a certain bull look more forward than some of the others ? I've read somewhere the bull can make up to 8 days difference in gestation length, but how scientific that conclusion was I don't know. |
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Post by larso on Sept 2, 2014 0:53:17 GMT -6
In New Zealand they look for Hereford bulls with a shorter gestation as a lot of their bulls go into the dairy industry, as Friesians are not noted as easy carvers. If a bull shortens up the gestation length by 3-4 days across a big herd it would also mean more milk. The bull I used over some of my heifers is a trait leader in gestation length from NZ so it will be interesting to see if there is any difference as I AI'ed then at same time.
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Post by larso on Sept 3, 2014 15:28:47 GMT -6
The last few days I've looked up as many research papers on gestation length in cattle as I could find. Some of the research was done in the 60's and 70's others later so there might be more up to date information on the subject.
* British breeds have a shorter gestation length than European or Brahman type cattle.
* Angus on average have a 1 day shorter length than Herefords, European up to 5-10 days longer and Brahman any thing up to 20 day's.
* It is hereditary, slightly more than BW, especially in a crossbreeding situation.
* Every day over the average i.e. Herefords 284-285 days, can effect the length of time ( up to 1.7 days )to rebreed
* Bull calves have a 1-2 day longer gestation than heifers.
* As the cow gets older her gestation length generally shortens rather than getting longer.
* It will or can effect BW.
Some of the members probably all ready know this information and how you use it is up to the individual, but I thought I would share it anyway.
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Post by Carlos (frmaiz) on Sept 3, 2014 16:37:15 GMT -6
285 + - 14 days. Heifers usually carry a day or so shorter than mature cows in my experience.
In the AHA webpage under the Education Center tab there is a Gestation Chart based upon a 283 days pregnancy. The AAA also considers 283 days. I am trying to find if calves born from cows IA'd fixed time November 15 are from IA or collective service immediately after. If the variance is +- 14 days it is impossible to assign a bull. Some thoughts: if there is so much variation in this character it should be possible to select for a shorter gestation length, which will have a positive effect on BW and rebreeding, therefore improving the average fertility of the herd. And a new EPD could be generated for those who like it! |
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Post by larso on Sept 3, 2014 17:24:15 GMT -6
One of the papers went on to say.
' The effect of short gestation length then, easier calving and more time for recovery for the mother. So short gestation length has a positive effect on calving ease and herd fertility.
Gestation length is seldom given the recognition that it deserves. Short gestation genetics are essentially free, that is they have no detrimental side effects (except where their influence makes BW lower than desirable) '
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Post by Glenn on Sept 3, 2014 17:35:56 GMT -6
There is a certain limit to low gestation. In other words "Don't Fu*& with mother nature"
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Post by Glenn on Sept 3, 2014 17:37:05 GMT -6
All systems especially respiratory system need time to develop properly.
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Post by Carlos (frmaiz) on Sept 3, 2014 17:49:21 GMT -6
There is a certain limit to low gestation. In other words "Don't Fu*& with mother nature" Whitin reasonable limits, yes. By the way, BW have been "Fu*&" by men. |
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Post by Glenn on Sept 3, 2014 18:13:04 GMT -6
You guys can tilt at that windmill if you want to. Lol. Good luck
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Post by Glenn on Sept 3, 2014 21:10:17 GMT -6
>>I am trying to find if calves born from cows IA'd fixed time November 15 are from IA or collective service immediately after. If the variance is +- 14 days it is impossible to assign a bull.<<
Probably why blood verification should be required on registrations. It would bogle the mind to know how many pedigrees are wrong and I mean up close 3-5 generations.
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Post by Glenn on Sept 3, 2014 21:10:38 GMT -6
>>I am trying to find if calves born from cows IA'd fixed time November 15 are from IA or collective service immediately after. If the variance is +- 14 days it is impossible to assign a bull.<<
Probably why blood verification should be required on registrations. It would bogle the mind to know how many pedigrees are wrong and I mean up close 3-5 generations.
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Post by tartancowgirl on Sept 4, 2014 3:44:41 GMT -6
The last few days I've looked up as many research papers on gestation length in cattle as I could find. Some of the research was done in the 60's and 70's others later so there might be more up to date information on the subject. * British breeds have a shorter gestation length than European or Brahman type cattle. * Angus on average have a 1 day shorter length than Herefords, European up to 5-10 days longer and Brahman any thing up to 20 day's. * It is hereditary, slightly more than BW, especially in a crossbreeding situation. * Every day over the average i.e. Herefords 284-285 days, can effect the length of time ( up to 1.7 days )to rebreed * Bull calves have a 1-2 day longer gestation than heifers. * As the cow gets older her gestation length generally shortens rather than getting longer. * It will or can effect BW. Some of the members probably all ready know this information and how you use it is up to the individual, but I thought I would share it anyway. In the UK breeders are using an EBV for bulls looking for shorter gestation length as it is thought to influence calving ease. I have always assumed the average to be 283 days. I was having trouble believing that it could be influenced by the bull but here is an anecdotal observation which I think is interesting. We have an older cow which has had 3 calves with us, all by AI using different bulls so we knew the insemination dates. The first calf was born on her due day (283), the second calf I was getting really worried as she was 10 days overdue, although the cow was really well. Everyone said "Oh it will be a bull calf - they're always carried longer!" Just as I was planning to induce her, out popped a normal heifer calf. With her next calf I kept a close eye on her and she calved on her due date again. We have the only registered calf by that second bull so we don't know if that would be normal for him but I can only assume it was an effect of the bull.
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Post by tartancowgirl on Sept 4, 2014 3:53:47 GMT -6
How many days are considered average in the Hereford breed and what is the normal variance? Heifers bred at 14-15 months have the same gestation length a mature cows? Obviously I don't have huge experience of this but my AIed heifers have had similar gestation lengths to the cows - I haven't noticed any difference, although when we've used the same bull they don't calve on the same day despite having been inseminated on the same day. |
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Post by picketwire on Sept 6, 2014 22:34:29 GMT -6
>>I am trying to find if calves born from cows IA'd fixed time November 15 are from IA or collective service immediately after. If the variance is +- 14 days it is impossible to assign a bull.<< Probably why blood verification should be required on registrations. It would bogle the mind to know how many pedigrees are wrong and I mean up close 3-5 generations. Best reason there is right there to lower the cost of simple DNA parent verification. |
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